Grinder gas, that is the gas which is released from roasted whole coffee beans when their internal cell structure is disrupted, such as during grinding of the beans and which also continues to be evolved from the disrupted and/or fractured beans for a short period thereafter, has long been recognized in the art as a highly desirable natural coffee aroma. A great deal of effort has been directed toward the development of a method for recovering and fixing a high percentage of grinder gas aromas on a substrate for subsequent addition to coffee products, particularly soluble coffee powder.
Clinton et al. in U.S. Pat. No. 3,021,218 disclose a method whereby a coffee aroma condensate is vaporized to admit the more volatile coffee aromas into void spaces of a container filled with soluble coffee. Johnston teaches addition of condensed grinder gas to chilled soluble coffee powder in U.S. Pat. No. 2,306,061. These two methods are similar in that grinder gas aromas are contacted directly with coffee particles in order to improve the aromatics of the coffee product. However, both methods fail to provide the convenience, stability, and high level of grinder gas fixation, desired in the coffee field.
Several methods for fixing grinder gas aromatics in a glyceride substrate are known in the art, such glycerides as coffee oil, bland-tasting vegetable oils, and triacetin being especially useful for this purpose. Katz in U.S. Pat. No. 3,939,291 teaches contacting condensed grinder gas and a glyceride in a pressure vessel at a temperature above the critical temperature of liquid carbon dioxide, then slowly venting the vessel while maintaining the temperature above carbon dioxide's critical temperature. Katz' method effectively prevents the formation of liquid carbon dioxide at any point during the glyceride aromatization procedure. Mahlmann discloses, in U.S. Pat. No. 3,979,528, contacting a glyceride and condensed grinder gas in a pressure vessel at a temperature of 70.degree. to 75.degree. F. and a pressure above 100 psia to enable aromatic transfer from the liquid carbon dioxide phase to the liquid glyceride phase, and then venting the vessel. Mahlmann's procedure involves repeated venting of said pressure vessel from a high pressure ranging from 75 to 120 psig, to a low pressure of 0 psig. Siedlecki et al. in U.S. Pat. No. 4,007,291 teach a procedure whereby a glyceride is contacted with condensed grinder gas in a pressure vessel at a temperature of 70.degree. to 85.degree. F. and a pressure in excess of 700 psig, then slowly venting the pressure vessel, preferably isothermally. Howland et al. in U.S. Pat. No. 4,119,736 disclose removal of a water phase from a pressure vessel containing condensed grinder gas at a pressure of in excess of 506.2 psia and a temperature of greater than 32.degree. F., contacting the demoisturized grinder gas with a glyceride, and slowly venting the pressure vessel. Howland et al. disclose that it is possible to separate aromas from the removed water phase, such as by vacuum distillation, and to reclaim or recycle vented aromatics.
It is an object of the present invention to produce an aromatized glyceride of improved quality which may be used to aromatize soluble coffee.
It is a further object of the invention to improve the organoleptic character of an aromatized glyceride such that it is more like freshly roasted and ground coffee grinder gas.
It is an additional object that the aromatized glyceride exhibit good stability both prior to and subsequent to its application to a coffee substrate.
It is yet another object that the process by which an aromatized glyceride is produced satisfying the above criteria, be controllable, reproducible, safe and efficient.